CI: Use iPhone 15 & iOS 18 (#3160)

Author: denrase

.github/workflows/flutter_test.yml

@@ -134,7 +134,7 @@ jobs:
         run: |
           case "${{ matrix.target }}" in
             ios)
-            device=$(xcrun simctl create sentryPhone com.apple.CoreSimulator.SimDeviceType.iPhone-14 com.apple.CoreSimulator.SimRuntime.iOS-17-0)
+            device=$(xcrun simctl create sentryPhone com.apple.CoreSimulator.SimDeviceType.iPhone-16 com.apple.CoreSimulator.SimRuntime.iOS-18-0)
             xcrun simctl boot ${device}
             echo "platform=iOS Simulator,id=${device}" >> "$GITHUB_OUTPUT"
             ;;